Uninterruptible power supplies (UPS) serve as back-up power supplies to critical electrical devices during outages of regular power supplies. The UPS is generally computer controlled and monitors the power supplied to the electrical device, switching on the back-up power supply if the normal power supply becomes insufficient. Therefore it is crucial that the UPS be reliable even after periods of minimal maintenance. A UPS typically draws its backup power from a set of lead-acid batteries connected in series and housed in a battery case. The battery cases are housed in a UPS cart with a front door that opens and allows the battery case to be slid into the cart and connected.
Current battery cases consist of a top piece and a bottom piece constructed of a non-conducting material, usually a heavy plastic. The bottom piece is divided into compartments by short fins, each compartment containing two or more batteries which have been adhered together. The batteries are wired in series and connected to an electrical connector mounted in an end panel of the bottom piece. The top piece is then secured to the bottom piece to form a generally rectangular container whose seam runs along the center of the container.
Battery cases provide for improved safety and handling of lead-acid batteries. As can be appreciated, lead-acid batteries pose hazards due to the possible leakage of acid contained within the battery. For example, acid leaked from a battery can cause short circuits and result in damage to equipment and an increased risk of fires. While conventional battery cases are able to contain leaked acid within the case when the case is positioned correctly on its bottom piece, the battery case during installation may be dropped or set down on a side having a seam through which the acid may leak. Conventional cases also do not effectively protect other batteries within the case from the leaked acid. The presence of the seam also limits the case to a single orientation within the UPS. Accordingly a different battery case has generally been required for each different style of UPS.
Further, the UPS electrical connections are located at the back of elongated narrow bays defined in the UPS cart for receiving the battery cases. The connection therefore has usually been made by hand with minimal space and poor lighting. Such a hand connection requires that the UPS be powered down to prevent injuries, thus defeating the purpose of a continuous backup power supply.
In an effort to eliminate manual coupling of the connectors, the connectors have been mounted on stiff springs for limited movement. The springs function to press the connector forward and thereby allow the connector members a limited amount of back and forth shifting in an effort to achieve coupling of the connectors when the battery cases are inserted. However, this type of adjustment has proven to be largely ineffective. To better align the connectors, the battery cases have been formed with guide members on their bottom surfaces for mating receipt in guiding grooves formed in the bays of the UPS shelves. However, connection is still difficult because of the stiffness of the springs and the weight of the cases, which can sometimes be over 100 pounds.